| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming device which controls the concentration of toner properly according to the condition of the operation of the copying machine. SOLUTION: In the image forming device in which a developing unit storing two-component developer containing carrier and toner is replenished with toner, developing-operation time is measured by a developing-time measuring means 35, and developing-operation quiescent time is also measured by a quiescent time measurement means 33. According to the result of each measurement, a selection means 39 selects a concentration detection value found by a toner- concentration detection means 13 or a detection value found by a toner- consumption quantitative detection means 31, thereby adapting the detection value matching the condition of the developing operation, and based on it a replenishment control means 34 replenishes the developing unit with the toner from a toner replenishment device. This enables proper toner-replenishment matching the condition of the developing operation, prevents erroneous detection of the concentration of the toner in the developing unit, and maintains the concentration of toner properly. |
